In the manufacture of electronic devices, wiring of various types and sizes is required to complete the necessary electrical connection for proper operation of the device. The wires used in this manufacture as formed with a conductive core, normally formed from a type of metal, surrounded by an insulting material sheath. The insulating material sheath is formed to closely conform to the shape of the conductive core, and is formed of a material that is both electrically insulating, and durable to provide effective insulation to the wiring.
However, because the wiring formed in this manner is utilized for making electrical connections in various types of devices, during the manufacture of the devices it is necessary to expose the ends of the conductive core of the wiring in order to facilitate the construction of the device. Therefore, when wiring having an insulating material sheath is utilized, portions of the sheath usually must be removed.
In prior art devices developed for removing portions of the insulating sheath, blades are utilized to cut through the sheath material such that it can be stripped off of the conductive core. These blades were designed to utilize one of two cutting methods. In the first, called the push cutting method, a pair of opposed blades are each formed with a generally flat cutting surface having a central notch formed therein. The notches are disposed in alignment with one another and are formed to have a radius approximately equal to the radius of the conductive core of the wiring being stripped. To remove the conductive sheath from the wiring, the wiring is positioned between the blades in alignment with the notches and the blades are moved towards each other. The cutting edges of the blades engage the insulating material sheath on both sides of the wiring and sever the portion to be removed from the remainder of the sheath. While the sheath material is being severed, the conductive core is located within the notches to limit the contact of the cutting surfaces with the core.
One significant drawback with regard to this cutting method is that, while it is possible to control the depth of the cut through the sheath at the center of each notch in the cutting surface, the cutting surface on each end of the notch can insufficiently sever the sheath, as the sheath is squeezed between the opposed blades. Further, if the blades are compressed further to sever the squeezed sections of the sheath, this can nick the conductive core, thereby reducing the current carrying capacity of the core.
As an alternative to the push cutting blades and method, a second cutting and stripping method involves the use of V-shaped blades. In this method, the blades each have a V-shaped opening formed in the cutting surface of the blade, with the cutting edge running completely along the periphery of the opening. The opening terminates in a rounded end that corresponds generally in shape to the circumference of the wiring to be cut and stripped using the blades.
In operation, the wiring is positioned between the blades, and the blades are subsequently moved towards one another. The V-shape of the openings in the blades urges the wiring towards the rounded ends of each blade until the wiring is captured in the rounded ends. During the movement of the wiring towards the capture position and at this point, the cutting edges on the sides and rounded ends of the openings engage and cut into the insulating material sheath. As a result of the shape of the rounded ends of the openings, any contact of the cutting edges with the conductive core of the wiring is limited, to minimize any nicking of the conductive core by the cutting edges of the blades.
However, while the shape of the rounded ends of the openings attempts to minimize contact of the cutting edges with the conductive core of the wiring, similarly to the issues with the push cutting blades and method, the V-shape blades and method cannot effectively control the depth of the cut into the sheath, such that the sheath is incompletely severed, and nicks in the conductive core occur.
Therefore, it is desirable to develop a cutting blade and method for utilizing the blade that provides a controlled-depth cut into the insulating material sheath on a coated wire to minimize nicking or otherwise damaging the conductive core of the wiring.